Yes, others previously created humbucking pickups by applying a preexisting method of noise cancellation to a transducer. Seth's take i.e bobbin, magnet, baseplate and cover dimensions, foot placement etc is the template used by Duncan, dimarzio, and everyone else, big and small, making aftermarket humbuckers.
The EMG 81 is the size it is so it can retrofit into a guitar that was previously loaded with buckers that follow Seth's design. 10$ Aliexpress buckers look like a PAF. If a kid walks into a shop and asks for a replacement humbucker, the dude behind the counter isn't going to plunk a Filtertron down on the counter.
'The humbucker as we know it', is carefully worded to allude to the popularity and longevity of the PAF, there's nothing in that statement claiming that Lover created anything fundamentally new.
Seth Lover was indeed the first; the first to design the pickup that everyone uses.